Templates are frequently used in design work for the drawing of circles. One type found in use is basically a thin flat plate with various sizes of circular holes manufactured into the plate; these holes corresponding to the sizes of circles that my be drawn. The template is moved over the drawing surface and positioned in the desired location so that a circle can be drawn.
Another form of circle template found in use, is the rotating circle template; which is essentially a thin flat plate that has a circular periphery. At the axis of this circular plate is a spring loaded pin with a conical point that when pushed into the drawing surface by finger pressure, allays the circular template to be rotated around the depressed pin. By placing the drawing means through any of the numerous eyelet sized holes manufactured in the template which are located progressively further from the central pin and rotating the said template as previously mentioned, the drawing means is guided in a circular path by the template so that a circle can be drawn on the drawing surface.
Both of the preceding templates mentioned, have a number of drawbacks. The first template mentioned carries a limited number of circles that can be drawn with one template. The cost of a full set of templates to produce a larger variety of circles is prohibitive. Another drawback presents itself if a designer wishes to draw circles in ink; there being the hazard of having the ink migrate between the template and the drawing surface thereby causing blotching on the said drawing surface. Still another drawback is seen when a plurality of concentric circles are drawn. Since the template must be repositioned for each new circle, concentricity is both difficult and time consuming.
The rotating circle template previously mentioned also has several drawbacks. For one; if ink is used to draw circles, blotching or smearing of the inked circle is possible due to the said circle template being rotated over the ink circle being drawn and thereby coming into contact with said circle. Furthermore, since a spring loaded pin is used under finger pressure, the designer using this template must maneuver the drawing means in one hand, around the other hand, which is being used to supply finger pressure to the spring loaded pin, thereby increasing the possibility of error by producing an unsatisfactory circle. Still a further drawback is caused due to the spring loaded pin covering over the axis of the circle being drawn. If the designer wishes to draw concentric circles at a later time from this position, there is great difficulty in finding the exact location where the spring loaded pin originally had been positioned into the drawing surface. Lastly, when using the said circle template to produce an arc tangential to converging right-angle lines, thereby forming a rounded corner on a drawing; this can only be accomplished by rotating the said template back and forth until the desired circle radius becomes tangential with said lines; this being time consuming and tedious.